The invention is directed to a position controller for pneumatic positioning devices and the like. Such positioning devices are disclosed, for example, in U.S. Pat. Nos. 4,922,952 and 4,925,498.
Position controllers for pneumatic positioning devices must be set with respect to their zero point after assembly. Usually, a zero point screw is turned until the drive rod of the positioning device just moves.
The allocation of the closed position of the positioning device to the zero position of the position control measuring system is not always the same due to dimensional deviations and variable allocation between drive rod and cone. The full range of the measuring system can therefore not always be used without readjustment of the zero point.